1. Field of the Invention
The present invention relates to a technical field of an optical apparatus and an imaging apparatus. More specifically, the present invention relates to a technical field for accelerating an operation of adjusting the quantity of light incident to an image sensing device while ensuring reliability of the operation with a configuration in which a polar liquid and a nonpolar liquid are sealed in a plurality of chambers being divided by a partition wall.
2. Description of the Related Art
Imaging apparatuses of various types, such as video cameras or still cameras, are provided with an optical apparatus that adjusts the quantity of light incident to an image sensing device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal-Oxide Semiconductor).
As examples of the optical apparatus, a mechanical iris mechanism, a mechanical shutter mechanism, and the like, in which a light quantity adjustment operation is performed by operating a singular, or plural, movable blade, are known.
However, the iris mechanism or the like that adjusts the quantity of light by operating the movable blade is necessary to have a driving mechanism and a driving source for operating the movable blade. Thus, it is difficult to achieve a reduction in the size of the imaging apparatus.
In addition, the adjustment of the quantity of light using the movable blade may generate noise during the movement of the movable blade. Moreover, refraction of light may occur in a so-called small aperture state where the quantity of light is limited by the movable blade to decrease the size of an opening through which light passes. Thus, resolution of a resulting image decreases. Particularly, in recent years, the pitch of pixels of the image sensing device has been decreasing, and it is therefore desirable to have a new optical apparatus for ensuring constant optical performance.
In order to solve the problems described above, as a substitute for the mechanical optical apparatus, an optical apparatus that adjusts the quantity of light by moving a polar liquid using an electrowetting phenomenon has been proposed in JP-A-2007-209112 and JP-A-2007-264278, for example.
The optical apparatus using the electrowetting phenomenon has a polar liquid and a nonpolar liquid which are sealed in a predetermined amount in respective chambers. When a voltage is applied to one electrode, the polar liquid is pulled towards the electrode and moved in a first direction. When a voltage is applied to the other electrode, the polar liquid is pulled towards the electrode and moved in a second direction.
In this way, by pulling the polar liquid towards the electrode to which the voltage is applied, an optical path is interrupted, for example, by the polar liquid when the polar liquid is moved in the first direction. On the other hand, the optical path is opened by the polar liquid when the polar liquid is moved in the second direction. Thus, the quantity of light is adjusted.
The optical apparatus disclosed in JP-A-2007-209112 accelerates the movement of the polar liquid by causing an electric field generated by the voltage applied to the electrode to act on a large area of the polar liquid and thus increasing the force acting on the polar liquid.
In addition, the optical apparatus disclosed in JP-A-2007-264278 has two polar liquids sealed in respective chambers and applies an electric field to each of the two polar liquids to move the two polar liquids in directions towards and away from each other so that they are repeatedly separated and combined.